Joule heat is generated during a motor operates having an iron core including plural electrical steel sheets laminated with one another. Portions which are easily affected by heat such as an insulating film covering a copper wire, and a terminal of a copper wire are included in the motor, and therefore, it is desirable to effectively release the Joule heat.
On the other hand, an insulative coating film is generally provided at a surface of an electrical steel sheet. This is mainly to secure insulation performance of electrical steel sheets laminated with one another.
However, heat conductivity of a conventional insulative coating film is significantly low compared to heat conductivity of metal. Accordingly, in an iron core including plural electrical steel sheets laminated with one another, the heat is difficult to be transferred in a lamination direction of the electrical steel sheets. Recently, the state in which the heat is difficult to be transferred in the lamination direction becomes to be seen as a problem in accordance with diversification of a shape of a motor and so on.